This invention is particularly efficacious because it provides a good feel to the surgeon (user friendly), it provides significant visibility of the surgical sight, the attachment is bendable at-will without kinking to afford easy access to the target, enhances visibility, it is rigid and avoids any distortions and wobbling of the cutter, it operates at a high speed (RPM), say, 80,000 to 90,000 RPM, it provides heat dissipation, a unique lubrication technique and it is disposable. It is paramount that a medical instrument or component that is disposable should be cost effective. What is meant by disposable in the context of this patent application is that the attachment, namely, the burr and its supporting structure (burr attachment) are detachable from the drill motor and the adapter and is disposable. In the prior art, for example, the burr and its extensions are made integral with the adapter (sometimes referred to as the clutch or clutching mechanism) so that in order to make the burr disposable, the adapter, being attached thereto, is, of necessity, also disposable. It is readily understood that this is a less desirable scenario because it is less cost effective.
A good example of the differences between a more cost effective disposable component and a less cost effective disposable component is a comparison with the present invention and the instruments disclosed in the US Publication No. 2005/0177168 invented by Brunett, et al and entitled HIGH SPEED SURGICAL CUTTING INSTRUMENT (which is incorporated in its entirety herein by reference). In the present invention the comparable medical instrument is comprised of a motor, an adapter and the Curved Burr Attachment which is essentially the same elements of the instrument disclosed in the Publication, although the terminology is different. The elements in the instrument disclosed in the Publication, supra, that compares to the Curved Burr Attachment is the wire and the cutter extending at the end of the wire and its support structure, the chuck mechanism and the motor. Since the wire/cutter and support mechanism also includes an integral chuck mechanism (comparable to the adapter of the present invention) that serves to connect to the motor, the disposable portion includes both the wire/cutter and its support mechanism, as well as the clutch mechanism. In contrast, the present invention merely disposes the burr attachment of the Curved Burr Attachment instrument and hence, the remaining portion of the instrument, namely, the adapter (the more expensive portions of the tool) are re-usable. Obviously, every portion of the tool may be disposable, but this is impractical to do because of the cost and obviously, the drill motor is a capital investment and has many uses. What the industry needs and desires is a tool, of this type, which is extremely small, (ball cutters range in 0.5 mm-2 mm) which includes a disposable burr that is substantially inexpensive and hence, cost effective.
This type of medical instrument, because of its size and speed that is required to perform certain medical procedures, under normal operational circumstances, it is limited to the amount of time it can be placed in continuous use. Under medical practices, it is well known that the surgeon in most instances typically perform a surgical procedure under a minute. This invention provides at least 2 minutes of continuous operation where the heat generated at the cutter will not adversely affect the nerves and other parts of the patient's anatomy.
This invention constitutes an improvement over the surgical instrument that is disclosed in U.S. Pat. No. 4,811,736 granted to Griggs et al on Mar. 14, 1989 and entitled SURGICAL DRILL AND BUR FOR USE THEREWITH and also being incorporated herein in its entirety by reference. This invention, like the structure disclosed in the '736 patent, supra, is intended to be utilized in performing, amongst other types of surgery, otological surgery. While the surgical drill of the '736 patent, supra, may be highly viable, it is limited in the potential available rotational or cutting speed, particularly, because it utilizes a plastic sleeve (journal) bearing. According to the patentee of the Publication, supra, the operational speed of the structure disclosed in the '736 patent, supra, is “less than 20,000 RPM.” The present invention is intended for use where the RPM is typically in the 80,000 range. Furthermore, like the differences between the structure disclosed in the Publication, supra, the present invention is completely different from the structure in the '736 patent, supra, and affords features that are not taught in this reference patent.
The aforementioned Publication, supra, is worthy of mention because, in addition to the features disclosed therein, the present invention includes features, that are unobvious and novel, and that constitute an improvement there over. As mentioned above, the Publication, supra, describes a cutting tool that is intended for surgical use for the same types of surgical procedures that are intended for use by the present invention. As disclosed therein the medical instrument describes structure that includes a cutting instrument assembly having a support tube, an inner wire assembly (bur), a cutting tip, a coupling chuck within a housing and a motor (not shown) for rotating the cutting tip. The present invention, while using different names, provides a motor, an adapter and the burr with a cutting tip, which is terminology that applies to both structures, albeit, that the present invention is designed differently than what is disclosed in the Publication, supra, The features of the present invention are, namely, without limitations, the Curved Burr Attachment which is disposable, it provides an enhanced thermal effectiveness, includes a lubrication delivery system and is bendable at-will by the operator without adverse effects. What this means is that the attachment may be bent in a normal or customary acceptable curvature at the factory, while also providing to the operator the option of changing the bend or angle of the attachment at-will while still maintaining the rigidity and structural integrity of the assembly. The present invention also provides to the user a medical instrument that is capable of being utilized a significant length of time to perform a particular operation because of the heat dissipation. And the Curved Burr Attachment is the only portion of the medical instrument that is disposable. This latter feature is an important distinction over the prior because no other component has to be disposed other than the disposable Curved Burr Attachment. Obviously. This makes the unit cost effective and leaves the more costly capital expenditures, the adapter, to be re-used. Hence, these features just described and that are afforded by the present invention are in addition to the features described in the Publication, supra, namely, high-speed operation with minimal impact of user visibility, minimized heat-build-up, and improved stiffness.
The following is an explanation to show and support the fact that the specific differences between the disposable portions of the present invention and the ones described in the Publication, supra. Referring to the Publication, supra, itself, it states that “The coupling chuck is secured to the proximal section of the inner wire assembly. To this end, the coupling chuck is adapted for coupling to a drive mechanism of a drill.” In comparison with the present invention, in the present invention the “coupling chuck” is referred to as an “adapter” and the wire assembly is referred to as “burr”. What is significant is that in the structure of the Publication the coupling chuck and wire assembly are united and form an integral unit and are un-separable after assembly. This means that for it to be disposable this entire unit would have to be disposed. In the present invention, the adapter and burr and its attendant hardware are separate items and the burr is removable from the adapter such that it is the only portion of the inventive surgical instrument that is disposable, resulting in a cost effective device. Obviously, in the present invention the adapter is re-usable for future use, as will be described in detail in the description to follow.
In addition to the aforementioned features of the present invention, namely, the ability to bend the burr at-will, and the burr being disposable in a cost effective manner, the particular manner in which lubrication is applied to the burr is unique. In the present invention the wire-shaft of the burr is surrounded by a coil wire that extends to approximately from the proximal end to the distal end of the wire-shaft and is oriented in such a manner that the helix formed by the coil wire is in a upward direction so that by placing grease at the distal end, the rotation of the wire-shaft causes the grease to migrate from the distal end to the proximate end, namely, in the upward direction.
In addition to the lubrication feature and the bending without the kinking feature of the present invention, the coil wire which is fixed and non-rotatable, also serves another function, i.e. it dissipates heat. This is accomplished by judiciously locating the coil wire between the inner wall of the support sleeve or tube of the burr and the wire-shaft such that the outer and inner edges of each coil touches both the side of the inner wall of the support sleeve and the outer periphery of the wire-shaft, respectively. This serves to conduct the heat away from the wire-shaft and from internally of the support sleeve. Distributing the heat dissipation load in this manner reduces the heat or slows down the heat at the cutter resulting in additional time that the Curved Burr Attachment can be in continuous use in a medical procedure. As one in this technology knows the heat generated by the cutter can adversely affect nerves and other portions of the anatomy.
Another function of the coil wire is that it permits the bending of the burr without causing kinking. In accordance with this invention, the burr attachment of the Curved Burr Attachment is bent at the factory and may be, at the option of the surgeon, bent at-will.